Chemistry: Periodic Table Concepts

Questions and Answers

What is a period of elements on the periodic table?

A period of elements on the periodic table is a horizontal row in which all the elements in that row have valence electrons in the same energy level.

What is a group of elements on the periodic table?

A group of elements is a vertical column on the periodic table in which all the elements have the same number of valence electrons.

What is a cation?

A cation is a positive ion.

Which is larger, a cation or its corresponding atom? Why?

A cation is smaller than its corresponding atom since it has lost electrons which gives the atom volume. Signup and view all the answers

What is an anion?

An anion is a negative ion. Signup and view all the answers

Which is larger, an anion or its corresponding atom? Why?

An anion is larger than its corresponding atom because it has gained electrons which gives the atom volume. Signup and view all the answers

How do the atomic radii vary within a period on the periodic table? Why?

As the atomic number increases, the atomic radii of the atoms decreases due to the increase in the positive-negative attraction between the nucleus and electrons. Signup and view all the answers

How do the atomic radii vary within a group on the periodic table? Why?

As atomic number increases, the atomic radii of the atom increases due to the increase in the shielding effect and since there are more electrons in more energy levels. Signup and view all the answers

What is ionization energy?

Ionization energy is the energy needed to remove an electron from an atom. Signup and view all the answers

How does ionization energy vary within a group on the periodic table? Why?

As atomic number increases, the ionization energy decreases since the shielding effect increases, resulting in the outer electrons being held less tightly. Signup and view all the answers

How does ionization energy vary within a period on the periodic table? Why?

As atomic number increases, the ionization energy increases since the positive-negative attraction is increasing, thus the outer electrons are being held more tightly. Signup and view all the answers

What is electronegativity?

Electronegativity is an arbitrary scale indicating an element's attraction for a shared pair of electrons. Signup and view all the answers

How does electronegativity vary within a group on the periodic table? Why?

As atomic number increases, electronegativity decreases due to an increase in the shielding effect making the outer electrons being held more loosely. Signup and view all the answers

How does electronegativity vary within a period on the periodic table? Why?

As atomic number increases, electronegativity increases since the elements are getting closer to an octet. Signup and view all the answers

Which group of elements would have the highest ionization energy? Why?

The group with the highest ionization energy is the noble gas group since this group of elements has an octet and is already stable and thus do not want to lose any electrons. Signup and view all the answers

Who is given credit for developing the modern day Periodic Table of Elements?

Dmitri Mendeleev. Signup and view all the answers

Know where the alkali metal, alkali earth metals, halogens, and noble gases are located on the Periodic Table.

1, 2, 17, and 18. Signup and view all the answers

How is the modern day Periodic Table different than Mendeleev's?

The modern day version includes the noble gases, is organized by atomic number not atomic weight, and his families were horizontal not vertical. Signup and view all the answers

Study Notes

Periodic Table Concepts

Periods are horizontal rows where elements share the same energy level for valence electrons.
Groups are vertical columns with elements that have the same number of valence electrons.

Ions

Cations are positive ions formed when an atom loses electrons, resulting in a smaller size than the original atom.
Anions are negative ions formed when an atom gains electrons, leading to a larger size than the original atom.

Atomic Radii Trends

Within a period, atomic radii decrease due to increased positive attraction from the nucleus as atomic number increases.
Within a group, atomic radii increase as atomic number rises because of added electron shells creating a shielding effect.

Ionization Energy

Ionization energy is the energy required to remove an electron from an atom.
In groups, ionization energy decreases with increasing atomic number due to the greater shielding effect that weakens the attraction to outer electrons.
In periods, ionization energy increases with atomic number because outer electrons are held more tightly due to stronger nuclear attraction.

Electronegativity

Electronegativity measures an atom's ability to attract shared electrons, ranging from 0.0 to 4.0.
Electronegativity decreases in groups as atomic number increases due to increased shielding, making outer electrons less tightly held.
Electronegativity increases in periods as atomic number increases because elements approach a stable octet configuration.

Group Characteristics

Noble gases (Group 18) possess the highest ionization energy due to their stable octet, making them reluctant to lose electrons.
Alkali metals are located in Group 1, alkaline earth metals in Group 2, halogens in Group 17, and noble gases in Group 18.

Historical Context

Dmitri Mendeleev is credited with creating the modern Periodic Table.
The modern Periodic Table differs from Mendeleev's original by including noble gases, organizing elements by atomic number rather than atomic weight, and arranging families vertically instead of horizontally.

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Description

Explore key concepts of the periodic table, including the definition of periods and groups, cations and anions, atomic radii trends, and ionization energy. This quiz will test your understanding of how these elements interrelate within the structure of the periodic table.